The invention relates to a method for manufacturing a polychromic and/or spatially polychromic or a monochrome colored ceramic body, whereby a monochrome colored body essentially is of one color, a polychromic colored body has a two-dimensional color scheme, and a spatially colored polychromic has any desired color schemes or color distributions in any desired spatially directions. In particular the invention relates to a procedure for manufacturing a colored dental ceramic blank of a type that is suitable for processing by CAD/CAM.
Recently the use of hydrostabilized zircon has become thoroughly implemented in dental technology in the area of full ceramics. The major reason for this is the high stability of the high-performance ceramic frame. The final application of color occurs in a full ceramic tooth replacement by applying an additional ceramic coat on the tooth replacement already milled to a form, such as crowns or bridges. The additional ceramic coat today is still very expensive, and every individual tooth replacement has to be applied individually by hand. A machine manufacture is not possible. Still, as proven by studies, aesthetic blended ceramics manufactured in this way that have excellent color coats and shaping possibilities have a five times greater burst rate than the tried and tested blended metal ceramics (VMK). Because of frequent claims and high manufacturing costs, aesthetic blended ceramics should be rejected. Without the possibilities for adding color that blended ceramics has, only one tooth replacement can be manufactured, which essentially has no aesthetics.
According to DE11 2009 001 253 WO 2008 098 157, WO 2013 055 432, WO 0046 168, WO 2004 110 959, DE 199 04 522 B4, DE 10 2008 026 980 A1, WO 00/46168 A1, WO 2011/156602 A2 and DE 20 2011 109 956 U1, WO 11 15 66 02, EP 2013 06 31 20, metal ion solutions and/or metal complex solutions and gels for coloring porous dental ceramics have been developed, which imitate the current single color basic body of a tooth. However, one should note that no single color tooth exists in the mouth of a patient. This is also explained in DE 10 2008 026 980 A1. On the corners of a tooth, such as on a cutting edge, color pigments accumulate, whereby these corners appear darker than the rest of the tooth. In a natural tooth, the color related darker dentine core is covered over by an ever thicker cutting edge material down to a transparent tooth cutting edge.
To the greatest extent possible, a simple and single color coloration is achieved by immersion or spraying of the replacement tooth. To be sure, the attempt is made using a brush or applications by drops to achieve tooth coloring structures or similar colorings on the replacement tooth, but with the known fluids, solutions, or gels no result identical to nature can be achieved, so that as a result there are significant color differences between natural teeth and a replacement tooth. In addition, it is known from DE 199 04 522 B4 that regardless of the application duration of the fluid or the solution or the gel from 2 minutes to 20 minutes, the same color tone is always achieved. The depth of the effect is also decisive for color development, particularly in the transition to another color. All teachings have shown that specific drying processes with long-term effects must be performed by dental technicians.
Another disadvantage of fluids or solutions results from the fact that drops cannot be applied according to the individual situation and are therefore uncontrollably distributed over the completely porous ceramic. For example, it is not possible to color only the crown edges or only the crown tips, since the color dispensing drops run straight to the corners or tips. Furthermore, with the application instruments, such as marking pens and brushes, air is coated in, or air that is already existing within the porous ceramic replacement tooth is completely sucked in when the porous ceramic is completely immersed, and as a result the enclosed air can cause there to be no filling of the porosities and subsequently lead to no coloring of the ceramic.
A brush used for applying the color has for example an uncontrollable supply of coloring fluid and/or color removing solutions and/or color removing materials and gels. Consequently there is a principle of chance as to how much coloring and/or color removing material is taken up by the brush. A drop too much can also not be avoided or corrected. Should this occur, the complete tooth replacement must be newly prepared or manufactured. All teachings include only the failure of color dispensing components or removal of color dispensing components.
The solutions and gels that are composed on a water or alcohol basis lie at the base of rapid evaporation. The evaporation, which for example arises through incorrect storage, increases the concentration of solutions and gels so that as a result the color tone is changed in an undesired fashion. Moreover, solutions or fluids or gels leave behind drops and run out, and thereby there is contamination, evaporation, and adhesion. That is why wearing protective clothing, protective gloves, and protective spectacles is the rule.
That is why if a crown or the tooth replacement has an aesthetic result, the characteristics that subsequently occur should be considered and implemented. For one thing, the dentine coating must have the basic tooth color of the patient. The dentine color and the strength of the cutting coating form the particular tooth color of the patient. The natural tooth while growing or through later wear and tear forms the three-dimensional color combination. Otherwise there is also an ever brighter color scheme from the dentine core all the way to the cutting edge. The tooth enamel can also partially show bright and/or transparent spots. In addition, in older patients, the dark dentine color crown edges are quite visible, and as a result the new tooth replacement must be adjusted accordingly. If the tooth replacement is not individualized manually, but manufactured automatically, for example a multiplicity of quite different ceramic blanks must be manufactured in order to achieve cost reductions and aesthetic results.
In a situation that differs from the previously described manufacturing methods, it is not the milled out tooth replacement or the porous tooth replacement frame that is colored, but the initial material for manufacture of the ceramic blank is colored, for example the ceramic powder or ceramic paste.
This solution is proposed by EP 202 4300, WO 2014 062 375, WO 02 09 6 12, U.S. Pat. No. 9,212,065 B2, DE 2020 090 187 24, EP 235 97 71 and EP 185 97 57. These teach the covering of the initial material, in particular of powders and pastes. The powder or pastes are poured on or applied, whereby each coating has a concrete color. In this way 7-10 coatings are necessary to achieve a two-dimensional color application or a two-dimensional color scheme. DE 2020 090 187 24, U.S. Pat. No. 9,119,696, WO 02 09 6 12 teach that these coatings are curved, meaning that other costs arise for special tools as well as for an expensive multi-powder application with a precise dose application distribution. In addition, manufacturing according to these teachings is limited to individual crowns. Moreover, EP 18 59 75 7 shows the difficulties that arise in the transitions from coating to color coating. It teaches that a coating in the transition zone should be laid out with intermediate coatings. With 7-10 coatings multiplied by the 16 basic tooth colors, hundreds of powder and paste mixing possibilities result, which in each case are associated with high costs, hundreds of batch test and monitoring costs, and enormous storage costs. The blanks are still sintered on. Since the baking ovens on quality grounds can bake only one tooth color, there are further increases in the energy costs. A color scheme within a color coating from inside to the outside, and thereby a three-dimensional colors scheme identical to nature, cannot be achieved with the manufacturing methods described here.
It is therefore the task of the invention to provide an inexpensive alternative manufacturing method for a monochrome, polychromic, and/or spatially polychromic colored ceramic body and an device for such manufacture.
For the solution, reference is made to a method according to claim 1.